Form 1099-B field reference
Form 1099-B Box 1e: Cost or other basis
Form 8949 destination
Column (e) — Cost or other basis
Reconcile this field with the rest of the transaction before calculating gain or loss. A Form 1099-B label does not override the official basis, holding-period, or adjustment rules.
Before filing
What to check
- Compare broker basis with purchase and transfer records.
- Include reinvested distributions and basis adjustments supported by records.
- Use Form 8949 adjustment codes and amounts when correcting reported basis.